The present invention relates to a method of continuous centrifugally casting of metals, especially steel. The present invention is especially directed to the casting of metal strands having a square, rectangular or generally non-circular cross-section in which the metal continuously passing through an ingot mold of corresponding cross-section is rotated by means of a rotating magnetic field.
It is well known that continuous casting of metal in which the liquid metal in the ingot mold is rotated about the axis of the latter presents various advantages as compared with the method of continuous casting in which the metal in the mold is not rotated, in that the quality of the produced casting is in the first-mentioned method considerably improved as far as the structure of the obtained solidified metal and the absence of inclusion of foreign matter in the same is concerned.
It is further well known that the metal may be rotated during the casting process by mechanical means by rotating the ingot mold and providing rotating means which extract the solidified metal from the mold, or, the liquid metal in the mold may be rotated electromagnetically by means of a rotating magnetic field created by a stationary polyphase inductor surrounding the cast product preferably at the level of the ingot mold.
At the present state of the development the two above-mentioned methods of rotating the liquid metal in the mold furnish products of substantially identical quality. Nevertheless, the method of rotating the liquid metal in the ingot mold by mechanical means has, as compared with the method of rotating the liquid metal in the mold by electromagnetic means, a number of major disadvantages, especially since the method of rotating the liquid metal by mechanical means cannot be employed in every type of continuous casting and for every type of cast products, since it necessarily requires rotation of the cast product about a vertical axis. Thus it is not possible to utilize a method in which the liquid metal in the mold is rotated by mechanical means during continuous casting of metal strands with a curved axis, nor during continuous casting of metal strand of non-circular cross-section. The centrifugal casting of metal strands in which the liquid metal is rotated by electromagnet means, on the other hand, may be more generally used as far as the type of apparatus for continuous casting and the form of the cast product is concerned. Installation for continuous casting of metal strands in which the liquid metal is continuously rotated during its passage through the ingot mold by electromagnet means are known in the art and for instance disclosed in the French Patent Nos. 2,279,500; 2,315,344 and the corresponding U.S. Pat. No. 4,026,346 and the U.S. patent application Ser. No. 748,301, as well as in the German Patent No. 1,159,516, which are herewith incorporated as references for showing such installations in detail.